diff --git a/lib/class-wp-theme-json-gutenberg.php b/lib/class-wp-theme-json-gutenberg.php
index 789e6b2a531836..0ad663064fe9ff 100644
--- a/lib/class-wp-theme-json-gutenberg.php
+++ b/lib/class-wp-theme-json-gutenberg.php
@@ -2680,7 +2680,7 @@ static function ( $pseudo_selector ) use ( $selector ) {
 		}
 
 		// 2. Generate and append the rules that use the general selector.
-		$block_rules .= static::to_ruleset( $selector, $declarations );
+		$block_rules .= static::to_ruleset( ":where($selector)", $declarations );
 
 		// 3. Generate and append the rules that use the duotone selector.
 		if ( isset( $block_metadata['duotone'] ) && ! empty( $declarations_duotone ) ) {
@@ -2697,7 +2697,7 @@ static function ( $pseudo_selector ) use ( $selector ) {
 
 		// 5. Generate and append the feature level rulesets.
 		foreach ( $feature_declarations as $feature_selector => $individual_feature_declarations ) {
-			$block_rules .= static::to_ruleset( $feature_selector, $individual_feature_declarations );
+			$block_rules .= static::to_ruleset( ":where($feature_selector)", $individual_feature_declarations );
 		}
 
 		// 6. Generate and append the style variation rulesets.
diff --git a/packages/block-editor/src/components/global-styles/test/use-global-styles-output.js b/packages/block-editor/src/components/global-styles/test/use-global-styles-output.js
index 5599fcfca19ab7..304c7f56fb101c 100644
--- a/packages/block-editor/src/components/global-styles/test/use-global-styles-output.js
+++ b/packages/block-editor/src/components/global-styles/test/use-global-styles-output.js
@@ -481,8 +481,8 @@ describe( 'global styles renderer', () => {
 
 			expect( toStyles( tree, blockSelectors ) ).toEqual(
 				'body {margin: 0;}body .is-layout-flow > .alignleft { float: left; margin-inline-start: 0; margin-inline-end: 2em; }body .is-layout-flow > .alignright { float: right; margin-inline-start: 2em; margin-inline-end: 0; }body .is-layout-flow > .aligncenter { margin-left: auto !important; margin-right: auto !important; }body .is-layout-constrained > .alignleft { float: left; margin-inline-start: 0; margin-inline-end: 2em; }body .is-layout-constrained > .alignright { float: right; margin-inline-start: 2em; margin-inline-end: 0; }body .is-layout-constrained > .aligncenter { margin-left: auto !important; margin-right: auto !important; }body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)) { max-width: var(--wp--style--global--content-size); margin-left: auto !important; margin-right: auto !important; }body .is-layout-constrained > .alignwide { max-width: var(--wp--style--global--wide-size); }body .is-layout-flex { display:flex; }body .is-layout-flex { flex-wrap: wrap; align-items: center; }body .is-layout-flex > * { margin: 0; }body .is-layout-grid { display:grid; }body .is-layout-grid > * { margin: 0; }' +
-					'body{background-color: red;margin: 10px;padding: 10px;}a:where(:not(.wp-element-button)){color: blue;}a:where(:not(.wp-element-button)):hover{color: orange;}a:where(:not(.wp-element-button)):focus{color: orange;}h1{font-size: 42px;}.wp-block-group{margin-top: 10px;margin-right: 20px;margin-bottom: 30px;margin-left: 40px;padding-top: 11px;padding-right: 22px;padding-bottom: 33px;padding-left: 44px;}h1,h2,h3,h4,h5,h6{color: orange;}h1 a:where(:not(.wp-element-button)),h2 a:where(:not(.wp-element-button)),h3 a:where(:not(.wp-element-button)),h4 a:where(:not(.wp-element-button)),h5 a:where(:not(.wp-element-button)),h6 a:where(:not(.wp-element-button)){color: hotpink;}h1 a:where(:not(.wp-element-button)):hover,h2 a:where(:not(.wp-element-button)):hover,h3 a:where(:not(.wp-element-button)):hover,h4 a:where(:not(.wp-element-button)):hover,h5 a:where(:not(.wp-element-button)):hover,h6 a:where(:not(.wp-element-button)):hover{color: red;}h1 a:where(:not(.wp-element-button)):focus,h2 a:where(:not(.wp-element-button)):focus,h3 a:where(:not(.wp-element-button)):focus,h4 a:where(:not(.wp-element-button)):focus,h5 a:where(:not(.wp-element-button)):focus,h6 a:where(:not(.wp-element-button)):focus{color: red;}' +
-					'.wp-block-image img, .wp-block-image .wp-crop-area{border-radius: 9999px;}.wp-block-image{color: red;}.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }' +
+					':where(body){background-color: red;margin: 10px;padding: 10px;}:where(a:where(:not(.wp-element-button))){color: blue;}a:where(:not(.wp-element-button)):hover{color: orange;}a:where(:not(.wp-element-button)):focus{color: orange;}:where(h1){font-size: 42px;}:where(.wp-block-group){margin-top: 10px;margin-right: 20px;margin-bottom: 30px;margin-left: 40px;padding-top: 11px;padding-right: 22px;padding-bottom: 33px;padding-left: 44px;}:where(h1,h2,h3,h4,h5,h6){color: orange;}:where(h1 a:where(:not(.wp-element-button)),h2 a:where(:not(.wp-element-button)),h3 a:where(:not(.wp-element-button)),h4 a:where(:not(.wp-element-button)),h5 a:where(:not(.wp-element-button)),h6 a:where(:not(.wp-element-button))){color: hotpink;}h1 a:where(:not(.wp-element-button)):hover,h2 a:where(:not(.wp-element-button)):hover,h3 a:where(:not(.wp-element-button)):hover,h4 a:where(:not(.wp-element-button)):hover,h5 a:where(:not(.wp-element-button)):hover,h6 a:where(:not(.wp-element-button)):hover{color: red;}h1 a:where(:not(.wp-element-button)):focus,h2 a:where(:not(.wp-element-button)):focus,h3 a:where(:not(.wp-element-button)):focus,h4 a:where(:not(.wp-element-button)):focus,h5 a:where(:not(.wp-element-button)):focus,h6 a:where(:not(.wp-element-button)):focus{color: red;}' +
+					':where(.wp-block-image img, .wp-block-image .wp-crop-area){border-radius: 9999px;}:where(.wp-block-image){color: red;}.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }' +
 					'.has-white-color{color: var(--wp--preset--color--white) !important;}.has-white-background-color{background-color: var(--wp--preset--color--white) !important;}.has-white-border-color{border-color: var(--wp--preset--color--white) !important;}.has-black-color{color: var(--wp--preset--color--black) !important;}.has-black-background-color{background-color: var(--wp--preset--color--black) !important;}.has-black-border-color{border-color: var(--wp--preset--color--black) !important;}h1.has-blue-color,h2.has-blue-color,h3.has-blue-color,h4.has-blue-color,h5.has-blue-color,h6.has-blue-color{color: var(--wp--preset--color--blue) !important;}h1.has-blue-background-color,h2.has-blue-background-color,h3.has-blue-background-color,h4.has-blue-background-color,h5.has-blue-background-color,h6.has-blue-background-color{background-color: var(--wp--preset--color--blue) !important;}h1.has-blue-border-color,h2.has-blue-border-color,h3.has-blue-border-color,h4.has-blue-border-color,h5.has-blue-border-color,h6.has-blue-border-color{border-color: var(--wp--preset--color--blue) !important;}'
 			);
 		} );
@@ -524,7 +524,7 @@ describe( 'global styles renderer', () => {
 
 			expect( toStyles( Object.freeze( tree ), blockSelectors ) ).toEqual(
 				'body {margin: 0;}body .is-layout-flow > .alignleft { float: left; margin-inline-start: 0; margin-inline-end: 2em; }body .is-layout-flow > .alignright { float: right; margin-inline-start: 2em; margin-inline-end: 0; }body .is-layout-flow > .aligncenter { margin-left: auto !important; margin-right: auto !important; }body .is-layout-constrained > .alignleft { float: left; margin-inline-start: 0; margin-inline-end: 2em; }body .is-layout-constrained > .alignright { float: right; margin-inline-start: 2em; margin-inline-end: 0; }body .is-layout-constrained > .aligncenter { margin-left: auto !important; margin-right: auto !important; }body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)) { max-width: var(--wp--style--global--content-size); margin-left: auto !important; margin-right: auto !important; }body .is-layout-constrained > .alignwide { max-width: var(--wp--style--global--wide-size); }body .is-layout-flex { display:flex; }body .is-layout-flex { flex-wrap: wrap; align-items: center; }body .is-layout-flex > * { margin: 0; }body .is-layout-grid { display:grid; }body .is-layout-grid > * { margin: 0; }' +
-					'.wp-image-spacing{padding-top: 1px;}.wp-image-border-color{border-color: red;}.wp-image-border{border-radius: 9999px;}.wp-image{color: red;}' +
+					':where(.wp-image-spacing){padding-top: 1px;}:where(.wp-image-border-color){border-color: red;}:where(.wp-image-border){border-radius: 9999px;}:where(.wp-image){color: red;}' +
 					'.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }'
 			);
 		} );
diff --git a/packages/block-editor/src/components/global-styles/use-global-styles-output.js b/packages/block-editor/src/components/global-styles/use-global-styles-output.js
index f1ba157d9c12fd..990cd6a534921d 100644
--- a/packages/block-editor/src/components/global-styles/use-global-styles-output.js
+++ b/packages/block-editor/src/components/global-styles/use-global-styles-output.js
@@ -844,7 +844,7 @@ export const toStyles = (
 					( [ cssSelector, declarations ] ) => {
 						if ( declarations.length ) {
 							const rules = declarations.join( ';' );
-							ruleset += `${ cssSelector }{${ rules };}`;
+							ruleset += `:where(${ cssSelector }){${ rules };}`;
 						}
 					}
 				);
@@ -937,7 +937,9 @@ export const toStyles = (
 				isTemplate
 			);
 			if ( declarations?.length ) {
-				ruleset += `${ selector }{${ declarations.join( ';' ) };}`;
+				ruleset += `:where(${ selector }){${ declarations.join(
+					';'
+				) };}`;
 			}
 
 			// Check for pseudo selector in `styles` and handle separately.
diff --git a/packages/block-editor/src/components/iframe/index.js b/packages/block-editor/src/components/iframe/index.js
index 4236bae62b1e7d..e59e564da3e6a8 100644
--- a/packages/block-editor/src/components/iframe/index.js
+++ b/packages/block-editor/src/components/iframe/index.js
@@ -244,12 +244,12 @@ function Iframe( {
 				height: auto !important;
 				min-height: 100%;
 			}
-
-			body {
+			/* Lowest specificity to not override global styles */
+			:where(body) {
 				margin: 0;
 				/* Default background color in case zoom out mode background
 				colors the html element */
-				background: white;
+				background-color: white;
 			}
 		</style>
 		${ styles }
diff --git a/phpunit/class-wp-theme-json-test.php b/phpunit/class-wp-theme-json-test.php
index 66929629110129..17dff10346e3a0 100644
--- a/phpunit/class-wp-theme-json-test.php
+++ b/phpunit/class-wp-theme-json-test.php
@@ -553,7 +553,7 @@ public function test_get_stylesheet() {
 		);
 
 		$variables = ':root{--wp--preset--color--grey: grey;--wp--preset--gradient--custom-gradient: linear-gradient(135deg,rgba(0,0,0) 0%,rgb(0,0,0) 100%);--wp--preset--font-size--small: 14px;--wp--preset--font-size--big: 41px;--wp--preset--font-family--arial: Arial, serif;}.wp-block-group{--wp--custom--base-font: 16;--wp--custom--line-height--small: 1.2;--wp--custom--line-height--medium: 1.4;--wp--custom--line-height--large: 1.8;}';
-		$styles    = static::$base_styles . 'body{color: var(--wp--preset--color--grey);}a:where(:not(.wp-element-button)){background-color: #333;color: #111;}.wp-element-button, .wp-block-button__link{box-shadow: 10px 10px 5px 0px rgba(0,0,0,0.66);}.wp-block-cover{min-height: unset;aspect-ratio: 16/9;}.wp-block-group{background: var(--wp--preset--gradient--custom-gradient);border-radius: 10px;min-height: 50vh;padding: 24px;}.wp-block-group a:where(:not(.wp-element-button)){color: #111;}.wp-block-heading{color: #123456;}.wp-block-heading a:where(:not(.wp-element-button)){background-color: #333;color: #111;font-size: 60px;}.wp-block-post-date{color: #123456;}.wp-block-post-date a:where(:not(.wp-element-button)){background-color: #777;color: #555;}.wp-block-post-excerpt{column-count: 2;}.wp-block-image{margin-bottom: 30px;}.wp-block-image img, .wp-block-image .wp-block-image__crop-area, .wp-block-image .components-placeholder{border-top-left-radius: 10px;border-bottom-right-radius: 1em;}.wp-block-image img, .wp-block-image .components-placeholder{filter: var(--wp--preset--duotone--custom-duotone);}';
+		$styles    = static::$base_styles . ':where(body){color: var(--wp--preset--color--grey);}:where(a:where(:not(.wp-element-button))){background-color: #333;color: #111;}:where(.wp-element-button, .wp-block-button__link){box-shadow: 10px 10px 5px 0px rgba(0,0,0,0.66);}:where(.wp-block-cover){min-height: unset;aspect-ratio: 16/9;}:where(.wp-block-group){background: var(--wp--preset--gradient--custom-gradient);border-radius: 10px;min-height: 50vh;padding: 24px;}:where(.wp-block-group a:where(:not(.wp-element-button))){color: #111;}:where(.wp-block-heading){color: #123456;}:where(.wp-block-heading a:where(:not(.wp-element-button))){background-color: #333;color: #111;font-size: 60px;}:where(.wp-block-post-date){color: #123456;}:where(.wp-block-post-date a:where(:not(.wp-element-button))){background-color: #777;color: #555;}:where(.wp-block-post-excerpt){column-count: 2;}:where(.wp-block-image){margin-bottom: 30px;}:where(.wp-block-image img, .wp-block-image .wp-block-image__crop-area, .wp-block-image .components-placeholder){border-top-left-radius: 10px;border-bottom-right-radius: 1em;}:where(.wp-block-image img, .wp-block-image .components-placeholder){filter: var(--wp--preset--duotone--custom-duotone);}';
 		$presets   = '.has-grey-color{color: var(--wp--preset--color--grey) !important;}.has-grey-background-color{background-color: var(--wp--preset--color--grey) !important;}.has-grey-border-color{border-color: var(--wp--preset--color--grey) !important;}.has-custom-gradient-gradient-background{background: var(--wp--preset--gradient--custom-gradient) !important;}.has-small-font-size{font-size: var(--wp--preset--font-size--small) !important;}.has-big-font-size{font-size: var(--wp--preset--font-size--big) !important;}.has-arial-font-family{font-family: var(--wp--preset--font-family--arial) !important;}';
 		$all       = $variables . $styles . $presets;
 
@@ -599,7 +599,7 @@ public function test_get_stylesheet_support_for_shorthand_and_longhand_values()
 			)
 		);
 
-		$styles = static::$base_styles . '.wp-block-group{border-radius: 10px;margin: 1em;padding: 24px;}.wp-block-image{margin-bottom: 30px;padding-top: 15px;}.wp-block-image img, .wp-block-image .wp-block-image__crop-area, .wp-block-image .components-placeholder{border-top-left-radius: 10px;border-bottom-right-radius: 1em;}';
+		$styles = static::$base_styles . ':where(.wp-block-group){border-radius: 10px;margin: 1em;padding: 24px;}:where(.wp-block-image){margin-bottom: 30px;padding-top: 15px;}:where(.wp-block-image img, .wp-block-image .wp-block-image__crop-area, .wp-block-image .components-placeholder){border-top-left-radius: 10px;border-bottom-right-radius: 1em;}';
 		$this->assertSame( $styles, $theme_json->get_stylesheet() );
 		$this->assertSame( $styles, $theme_json->get_stylesheet( array( 'styles' ) ) );
 	}
@@ -712,7 +712,7 @@ public function test_get_stylesheet_preset_rules_come_after_block_rules() {
 			)
 		);
 
-		$styles    = static::$base_styles . '.wp-block-group{color: red;}';
+		$styles    = static::$base_styles . ':where(.wp-block-group){color: red;}';
 		$presets   = '.wp-block-group.has-grey-color{color: var(--wp--preset--color--grey) !important;}.wp-block-group.has-grey-background-color{background-color: var(--wp--preset--color--grey) !important;}.wp-block-group.has-grey-border-color{border-color: var(--wp--preset--color--grey) !important;}';
 		$variables = '.wp-block-group{--wp--preset--color--grey: grey;}';
 
@@ -799,7 +799,7 @@ public function test_get_stylesheet_preset_values_are_marked_as_important() {
 		);
 
 		$this->assertSame(
-			':root{--wp--preset--color--grey: grey;}' . static::$base_styles . 'p{background-color: blue;color: red;font-size: 12px;line-height: 1.3;}.has-grey-color{color: var(--wp--preset--color--grey) !important;}.has-grey-background-color{background-color: var(--wp--preset--color--grey) !important;}.has-grey-border-color{border-color: var(--wp--preset--color--grey) !important;}',
+			':root{--wp--preset--color--grey: grey;}' . static::$base_styles . ':where(p){background-color: blue;color: red;font-size: 12px;line-height: 1.3;}.has-grey-color{color: var(--wp--preset--color--grey) !important;}.has-grey-background-color{background-color: var(--wp--preset--color--grey) !important;}.has-grey-border-color{border-color: var(--wp--preset--color--grey) !important;}',
 			$theme_json->get_stylesheet()
 		);
 	}
@@ -837,7 +837,7 @@ public function test_get_stylesheet_handles_whitelisted_element_pseudo_selectors
 			)
 		);
 
-		$element_styles = 'a:where(:not(.wp-element-button)){background-color: red;color: green;}a:where(:not(.wp-element-button)):hover{background-color: green;color: red;font-size: 10em;text-transform: uppercase;}a:where(:not(.wp-element-button)):focus{background-color: black;color: yellow;}';
+		$element_styles = ':where(a:where(:not(.wp-element-button))){background-color: red;color: green;}:where(a:where(:not(.wp-element-button)):hover){background-color: green;color: red;font-size: 10em;text-transform: uppercase;}:where(a:where(:not(.wp-element-button)):focus){background-color: black;color: yellow;}';
 
 		$expected = static::$base_styles . $element_styles;
 
@@ -874,7 +874,7 @@ public function test_get_stylesheet_handles_only_pseudo_selector_rules_for_given
 			)
 		);
 
-		$element_styles = 'a:where(:not(.wp-element-button)):hover{background-color: green;color: red;font-size: 10em;text-transform: uppercase;}a:where(:not(.wp-element-button)):focus{background-color: black;color: yellow;}';
+		$element_styles = ':where(a:where(:not(.wp-element-button)):hover){background-color: green;color: red;font-size: 10em;text-transform: uppercase;}:where(a:where(:not(.wp-element-button)):focus){background-color: black;color: yellow;}';
 
 		$expected = static::$base_styles . $element_styles;
 
@@ -911,7 +911,7 @@ public function test_get_stylesheet_ignores_pseudo_selectors_on_non_whitelisted_
 			)
 		);
 
-		$element_styles = 'h4{background-color: red;color: green;}';
+		$element_styles = ':where(h4){background-color: red;color: green;}';
 
 		$expected = static::$base_styles . $element_styles;
 
@@ -948,7 +948,7 @@ public function test_get_stylesheet_ignores_non_whitelisted_pseudo_selectors() {
 			)
 		);
 
-		$element_styles = 'a:where(:not(.wp-element-button)){background-color: red;color: green;}a:where(:not(.wp-element-button)):hover{background-color: green;color: red;}';
+		$element_styles = ':where(a:where(:not(.wp-element-button))){background-color: red;color: green;}:where(a:where(:not(.wp-element-button)):hover){background-color: green;color: red;}';
 
 		$expected = static::$base_styles . $element_styles;
 
@@ -994,7 +994,7 @@ public function test_get_stylesheet_handles_priority_of_elements_vs_block_elemen
 			)
 		);
 
-		$element_styles = '.wp-block-group a:where(:not(.wp-element-button)){background-color: red;color: green;}.wp-block-group a:where(:not(.wp-element-button)):hover{background-color: green;color: red;font-size: 10em;text-transform: uppercase;}.wp-block-group a:where(:not(.wp-element-button)):focus{background-color: black;color: yellow;}';
+		$element_styles = ':where(.wp-block-group a:where(:not(.wp-element-button))){background-color: red;color: green;}:where(.wp-block-group a:where(:not(.wp-element-button)):hover){background-color: green;color: red;font-size: 10em;text-transform: uppercase;}:where(.wp-block-group a:where(:not(.wp-element-button)):focus){background-color: black;color: yellow;}';
 
 		$expected = static::$base_styles . $element_styles;
 
@@ -1039,7 +1039,7 @@ public function test_get_stylesheet_handles_whitelisted_block_level_element_pseu
 			)
 		);
 
-		$element_styles = 'a:where(:not(.wp-element-button)){background-color: red;color: green;}a:where(:not(.wp-element-button)):hover{background-color: green;color: red;}.wp-block-group a:where(:not(.wp-element-button)):hover{background-color: black;color: yellow;}';
+		$element_styles = ':where(a:where(:not(.wp-element-button))){background-color: red;color: green;}:where(a:where(:not(.wp-element-button)):hover){background-color: green;color: red;}:where(.wp-block-group a:where(:not(.wp-element-button)):hover){background-color: black;color: yellow;}';
 
 		$expected = static::$base_styles . $element_styles;
 
@@ -1101,7 +1101,7 @@ public function test_get_stylesheet_with_deprecated_feature_level_selectors() {
 		);
 
 		$base_styles   = ':root{--wp--preset--color--green: green;}' . static::$base_styles;
-		$block_styles  = '.wp-block-test, .wp-block-test__wrapper{color: green;}.wp-block-test .inner, .wp-block-test__wrapper .inner{border-radius: 9999px;padding: 20px;}.wp-block-test .sub-heading, .wp-block-test__wrapper .sub-heading{font-size: 3em;}';
+		$block_styles  = ':where(.wp-block-test, .wp-block-test__wrapper){color: green;}:where(.wp-block-test .inner, .wp-block-test__wrapper .inner){border-radius: 9999px;padding: 20px;}:where(.wp-block-test .sub-heading, .wp-block-test__wrapper .sub-heading){font-size: 3em;}';
 		$preset_styles = '.has-green-color{color: var(--wp--preset--color--green) !important;}.has-green-background-color{background-color: var(--wp--preset--color--green) !important;}.has-green-border-color{border-color: var(--wp--preset--color--green) !important;}';
 		$expected      = $base_styles . $block_styles . $preset_styles;
 
@@ -1163,7 +1163,7 @@ public function test_get_stylesheet_with_block_json_selectors() {
 		);
 
 		$base_styles   = ':root{--wp--preset--color--green: green;}' . static::$base_styles;
-		$block_styles  = '.custom-root-selector{background-color: grey;padding: 20px;}.custom-root-selector img{border-radius: 9999px;}.custom-root-selector > figcaption{color: navy;font-size: 3em;}';
+		$block_styles  = ':where(.custom-root-selector){background-color: grey;padding: 20px;}:where(.custom-root-selector img){border-radius: 9999px;}:where(.custom-root-selector > figcaption){color: navy;font-size: 3em;}';
 		$preset_styles = '.has-green-color{color: var(--wp--preset--color--green) !important;}.has-green-background-color{background-color: var(--wp--preset--color--green) !important;}.has-green-border-color{border-color: var(--wp--preset--color--green) !important;}';
 		$expected      = $base_styles . $block_styles . $preset_styles;
 
@@ -1332,7 +1332,7 @@ public function test_get_stylesheet_generates_valid_block_gap_values_and_skips_n
 
 		$this->assertSame(
 			'body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.wp-site-blocks) > * { margin-block-start: 1rem; margin-block-end: 0; }:where(.wp-site-blocks) > :first-child:first-child { margin-block-start: 0; }:where(.wp-site-blocks) > :last-child:last-child { margin-block-end: 0; }:root { --wp--style--block-gap: 1rem; }:where(body .is-layout-flow)  > :first-child:first-child{margin-block-start: 0;}:where(body .is-layout-flow)  > :last-child:last-child{margin-block-end: 0;}:where(body .is-layout-flow)  > *{margin-block-start: 1rem;margin-block-end: 0;}:where(body .is-layout-constrained)  > :first-child:first-child{margin-block-start: 0;}:where(body .is-layout-constrained)  > :last-child:last-child{margin-block-end: 0;}:where(body .is-layout-constrained)  > *{margin-block-start: 1rem;margin-block-end: 0;}:where(body .is-layout-flex) {gap: 1rem;}:where(body .is-layout-grid) {gap: 1rem;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}' .
-			'.wp-block-post-content{color: gray;}.wp-block-social-links-is-layout-flow > :first-child:first-child{margin-block-start: 0;}.wp-block-social-links-is-layout-flow > :last-child:last-child{margin-block-end: 0;}.wp-block-social-links-is-layout-flow > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-social-links-is-layout-constrained > :first-child:first-child{margin-block-start: 0;}.wp-block-social-links-is-layout-constrained > :last-child:last-child{margin-block-end: 0;}.wp-block-social-links-is-layout-constrained > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-social-links-is-layout-flex{gap: 0;}.wp-block-social-links-is-layout-grid{gap: 0;}.wp-block-buttons-is-layout-flow > :first-child:first-child{margin-block-start: 0;}.wp-block-buttons-is-layout-flow > :last-child:last-child{margin-block-end: 0;}.wp-block-buttons-is-layout-flow > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-buttons-is-layout-constrained > :first-child:first-child{margin-block-start: 0;}.wp-block-buttons-is-layout-constrained > :last-child:last-child{margin-block-end: 0;}.wp-block-buttons-is-layout-constrained > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-buttons-is-layout-flex{gap: 0;}.wp-block-buttons-is-layout-grid{gap: 0;}',
+			':where(.wp-block-post-content){color: gray;}.wp-block-social-links-is-layout-flow > :first-child:first-child{margin-block-start: 0;}.wp-block-social-links-is-layout-flow > :last-child:last-child{margin-block-end: 0;}.wp-block-social-links-is-layout-flow > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-social-links-is-layout-constrained > :first-child:first-child{margin-block-start: 0;}.wp-block-social-links-is-layout-constrained > :last-child:last-child{margin-block-end: 0;}.wp-block-social-links-is-layout-constrained > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-social-links-is-layout-flex{gap: 0;}.wp-block-social-links-is-layout-grid{gap: 0;}.wp-block-buttons-is-layout-flow > :first-child:first-child{margin-block-start: 0;}.wp-block-buttons-is-layout-flow > :last-child:last-child{margin-block-end: 0;}.wp-block-buttons-is-layout-flow > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-buttons-is-layout-constrained > :first-child:first-child{margin-block-start: 0;}.wp-block-buttons-is-layout-constrained > :last-child:last-child{margin-block-end: 0;}.wp-block-buttons-is-layout-constrained > *{margin-block-start: 0;margin-block-end: 0;}.wp-block-buttons-is-layout-flex{gap: 0;}.wp-block-buttons-is-layout-grid{gap: 0;}',
 			$theme_json->get_stylesheet()
 		);
 	}
@@ -1364,7 +1364,7 @@ public function test_get_stylesheet_returns_outline_styles() {
 			)
 		);
 
-		$element_styles = '.wp-element-button, .wp-block-button__link{outline-color: red;outline-offset: 3px;outline-style: dashed;outline-width: 3px;}.wp-element-button:hover, .wp-block-button__link:hover{outline-color: blue;outline-offset: 3px;outline-style: solid;outline-width: 3px;}';
+		$element_styles = ':where(.wp-element-button, .wp-block-button__link){outline-color: red;outline-offset: 3px;outline-style: dashed;outline-width: 3px;}:where(.wp-element-button:hover, .wp-block-button__link:hover){outline-color: blue;outline-offset: 3px;outline-style: solid;outline-width: 3px;}';
 
 		$expected = static::$base_styles . $element_styles;
 		$this->assertSame( $expected, $theme_json->get_stylesheet() );
@@ -1389,7 +1389,7 @@ public function test_get_stylesheet_custom_root_selector() {
 		// Results also include root site blocks styles which hard code
 		// `body { margin: 0; }`.
 		$this->assertSame(
-			'body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }.custom{color: teal;}',
+			'body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.custom){color: teal;}',
 			$actual
 		);
 	}
@@ -1448,7 +1448,7 @@ public function test_get_stylesheet_generates_fluid_typography_values() {
 
 		// Results also include root site blocks styles.
 		$this->assertSame(
-			':root{--wp--preset--font-size--pickles: clamp(14px, 0.875rem + ((1vw - 3.2px) * 0.156), 16px);--wp--preset--font-size--toast: clamp(14.642px, 0.915rem + ((1vw - 3.2px) * 0.575), 22px);}body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}body{font-size: clamp(0.875em, 0.875rem + ((1vw - 0.2em) * 0.156), 1em);}h1{font-size: clamp(50.171px, 3.136rem + ((1vw - 3.2px) * 3.893), 100px);}.wp-block-test-clamp-me{font-size: clamp(27.894px, 1.743rem + ((1vw - 3.2px) * 1.571), 48px);}.has-pickles-font-size{font-size: var(--wp--preset--font-size--pickles) !important;}.has-toast-font-size{font-size: var(--wp--preset--font-size--toast) !important;}',
+			':root{--wp--preset--font-size--pickles: clamp(14px, 0.875rem + ((1vw - 3.2px) * 0.156), 16px);--wp--preset--font-size--toast: clamp(14.642px, 0.915rem + ((1vw - 3.2px) * 0.575), 22px);}body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}:where(body){font-size: clamp(0.875em, 0.875rem + ((1vw - 0.2em) * 0.156), 1em);}:where(h1){font-size: clamp(50.171px, 3.136rem + ((1vw - 3.2px) * 3.893), 100px);}:where(.wp-block-test-clamp-me){font-size: clamp(27.894px, 1.743rem + ((1vw - 3.2px) * 1.571), 48px);}.has-pickles-font-size{font-size: var(--wp--preset--font-size--pickles) !important;}.has-toast-font-size{font-size: var(--wp--preset--font-size--toast) !important;}',
 			$theme_json->get_stylesheet()
 		);
 	}
@@ -3517,7 +3517,7 @@ public function test_get_property_value_valid() {
 			)
 		);
 
-		$color_styles = 'body{background-color: #ffffff;color: #000000;}.wp-element-button, .wp-block-button__link{background-color: #000000;color: #ffffff;}';
+		$color_styles = ':where(body){background-color: #ffffff;color: #000000;}:where(.wp-element-button, .wp-block-button__link){background-color: #000000;color: #ffffff;}';
 		$expected     = static::$base_styles . $color_styles;
 		$this->assertSame( $expected, $theme_json->get_stylesheet() );
 	}
@@ -3595,7 +3595,7 @@ public function test_get_property_value_loop() {
 			)
 		);
 
-		$color_styles = 'body{background-color: #ffffff;}.wp-element-button, .wp-block-button__link{color: #ffffff;}';
+		$color_styles = ':where(body){background-color: #ffffff;}:where(.wp-element-button, .wp-block-button__link){color: #ffffff;}';
 		$expected     = static::$base_styles . $color_styles;
 		$this->assertSame( $expected, $theme_json->get_stylesheet() );
 	}
@@ -3628,7 +3628,7 @@ public function test_get_property_value_recursion() {
 			)
 		);
 
-		$color_styles = 'body{background-color: #ffffff;color: #ffffff;}.wp-element-button, .wp-block-button__link{color: #ffffff;}';
+		$color_styles = ':where(body){background-color: #ffffff;color: #ffffff;}:where(.wp-element-button, .wp-block-button__link){color: #ffffff;}';
 		$expected     = static::$base_styles . $color_styles;
 		$this->assertSame( $expected, $theme_json->get_stylesheet() );
 	}
@@ -3652,7 +3652,7 @@ public function test_get_property_value_self() {
 			)
 		);
 
-		$color_styles = 'body{background-color: #ffffff;}';
+		$color_styles = ':where(body){background-color: #ffffff;}';
 		$expected     = static::$base_styles . $color_styles;
 		$this->assertSame( $expected, $theme_json->get_stylesheet() );
 	}
@@ -3682,7 +3682,7 @@ public function test_get_styles_for_block_with_padding_aware_alignments() {
 			'selector' => 'body',
 		);
 
-		$expected    = 'body { margin: 0; }.wp-site-blocks { padding-top: var(--wp--style--root--padding-top); padding-bottom: var(--wp--style--root--padding-bottom); }.has-global-padding { padding-right: var(--wp--style--root--padding-right); padding-left: var(--wp--style--root--padding-left); }.has-global-padding :where(.has-global-padding:not(.wp-block-block)) { padding-right: 0; padding-left: 0; }.has-global-padding > .alignfull { margin-right: calc(var(--wp--style--root--padding-right) * -1); margin-left: calc(var(--wp--style--root--padding-left) * -1); }.has-global-padding :where(.has-global-padding:not(.wp-block-block)) > .alignfull { margin-right: 0; margin-left: 0; }.has-global-padding > .alignfull:where(:not(.has-global-padding):not(.is-layout-flex):not(.is-layout-grid)) > :where([class*="wp-block-"]:not(.alignfull):not([class*="__"]),.wp-block:not(.alignfull),p,h1,h2,h3,h4,h5,h6,ul,ol) { padding-right: var(--wp--style--root--padding-right); padding-left: var(--wp--style--root--padding-left); }.has-global-padding :where(.has-global-padding) > .alignfull:where(:not(.has-global-padding)) > :where([class*="wp-block-"]:not(.alignfull):not([class*="__"]),.wp-block:not(.alignfull),p,h1,h2,h3,h4,h5,h6,ul,ol) { padding-right: 0; padding-left: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}body{--wp--style--root--padding-top: 10px;--wp--style--root--padding-right: 12px;--wp--style--root--padding-bottom: 10px;--wp--style--root--padding-left: 12px;}';
+		$expected    = 'body { margin: 0; }.wp-site-blocks { padding-top: var(--wp--style--root--padding-top); padding-bottom: var(--wp--style--root--padding-bottom); }.has-global-padding { padding-right: var(--wp--style--root--padding-right); padding-left: var(--wp--style--root--padding-left); }.has-global-padding :where(.has-global-padding:not(.wp-block-block)) { padding-right: 0; padding-left: 0; }.has-global-padding > .alignfull { margin-right: calc(var(--wp--style--root--padding-right) * -1); margin-left: calc(var(--wp--style--root--padding-left) * -1); }.has-global-padding :where(.has-global-padding:not(.wp-block-block)) > .alignfull { margin-right: 0; margin-left: 0; }.has-global-padding > .alignfull:where(:not(.has-global-padding):not(.is-layout-flex):not(.is-layout-grid)) > :where([class*="wp-block-"]:not(.alignfull):not([class*="__"]),.wp-block:not(.alignfull),p,h1,h2,h3,h4,h5,h6,ul,ol) { padding-right: var(--wp--style--root--padding-right); padding-left: var(--wp--style--root--padding-left); }.has-global-padding :where(.has-global-padding) > .alignfull:where(:not(.has-global-padding)) > :where([class*="wp-block-"]:not(.alignfull):not([class*="__"]),.wp-block:not(.alignfull),p,h1,h2,h3,h4,h5,h6,ul,ol) { padding-right: 0; padding-left: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}:where(body){--wp--style--root--padding-top: 10px;--wp--style--root--padding-right: 12px;--wp--style--root--padding-bottom: 10px;--wp--style--root--padding-left: 12px;}';
 		$root_rules  = $theme_json->get_root_layout_rules( WP_Theme_JSON_Gutenberg::ROOT_BLOCK_SELECTOR, $metadata );
 		$style_rules = $theme_json->get_styles_for_block( $metadata );
 		$this->assertSame( $expected, $root_rules . $style_rules );
@@ -3710,7 +3710,7 @@ public function test_get_styles_for_block_without_padding_aware_alignments() {
 			'selector' => 'body',
 		);
 
-		$expected    = static::$base_styles . 'body{padding-top: 10px;padding-right: 12px;padding-bottom: 10px;padding-left: 12px;}';
+		$expected    = static::$base_styles . ':where(body){padding-top: 10px;padding-right: 12px;padding-bottom: 10px;padding-left: 12px;}';
 		$root_rules  = $theme_json->get_root_layout_rules( WP_Theme_JSON_Gutenberg::ROOT_BLOCK_SELECTOR, $metadata );
 		$style_rules = $theme_json->get_styles_for_block( $metadata );
 		$this->assertSame( $expected, $root_rules . $style_rules );
@@ -4680,7 +4680,7 @@ public function data_update_separator_declarations() {
 						'background' => 'blue',
 					),
 				),
-				'expected_output' => static::$base_styles . '.wp-block-separator{background-color: blue;color: blue;}',
+				'expected_output' => static::$base_styles . ':where(.wp-block-separator){background-color: blue;color: blue;}',
 			),
 			// If background and text are defined, do not include border-color, as text color is enough.
 			'background and text, no border-color' => array(
@@ -4690,7 +4690,7 @@ public function data_update_separator_declarations() {
 						'text'       => 'red',
 					),
 				),
-				'expected_output' => static::$base_styles . '.wp-block-separator{background-color: blue;color: red;}',
+				'expected_output' => static::$base_styles . ':where(.wp-block-separator){background-color: blue;color: red;}',
 			),
 			// If only text is defined, do not include border-color, as by itself is enough.
 			'only text'                            => array(
@@ -4699,7 +4699,7 @@ public function data_update_separator_declarations() {
 						'text' => 'red',
 					),
 				),
-				'expected_output' => static::$base_styles . '.wp-block-separator{color: red;}',
+				'expected_output' => static::$base_styles . ':where(.wp-block-separator){color: red;}',
 			),
 			// If background, text, and border-color are defined, include everything, CSS specificity will decide which to apply.
 			'background, text, and border-color'   => array(
@@ -4712,7 +4712,7 @@ public function data_update_separator_declarations() {
 						'color' => 'pink',
 					),
 				),
-				'expected_output' => static::$base_styles . '.wp-block-separator{background-color: blue;border-color: pink;color: red;}',
+				'expected_output' => static::$base_styles . ':where(.wp-block-separator){background-color: blue;border-color: pink;color: red;}',
 			),
 			// If background and border color are defined, include everything, CSS specificity will decide which to apply.
 			'background, and border-color'         => array(
@@ -4724,7 +4724,7 @@ public function data_update_separator_declarations() {
 						'color' => 'pink',
 					),
 				),
-				'expected_output' => static::$base_styles . '.wp-block-separator{background-color: blue;border-color: pink;}',
+				'expected_output' => static::$base_styles . ':where(.wp-block-separator){background-color: blue;border-color: pink;}',
 			),
 		);
 	}
@@ -4788,7 +4788,7 @@ public function test_get_shadow_styles_for_blocks() {
 		);
 
 		$global_styles   = ':root{--wp--preset--shadow--natural: 5px 5px 0 0 black;}' . static::$base_styles;
-		$element_styles  = 'a:where(:not(.wp-element-button)){box-shadow: var(--wp--preset--shadow--natural);}.wp-element-button, .wp-block-button__link{box-shadow: var(--wp--preset--shadow--natural);}p{box-shadow: var(--wp--preset--shadow--natural);}';
+		$element_styles  = ':where(a:where(:not(.wp-element-button))){box-shadow: var(--wp--preset--shadow--natural);}:where(.wp-element-button, .wp-block-button__link){box-shadow: var(--wp--preset--shadow--natural);}:where(p){box-shadow: var(--wp--preset--shadow--natural);}';
 		$expected_styles = $global_styles . $element_styles;
 		$this->assertSame( $expected_styles, $theme_json->get_stylesheet() );
 	}
@@ -4835,7 +4835,7 @@ public function test_get_top_level_background_image_styles() {
 			)
 		);
 
-		$expected_styles = "body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}html{min-height: calc(100% - var(--wp-admin--admin-bar--height, 0px));}body{background-image: url('http://example.org/image.png');background-position: center center;background-repeat: no-repeat;background-size: contain;}";
+		$expected_styles = "body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}html{min-height: calc(100% - var(--wp-admin--admin-bar--height, 0px));}:where(body){background-image: url('http://example.org/image.png');background-position: center center;background-repeat: no-repeat;background-size: contain;}";
 		$this->assertSame( $expected_styles, $theme_json->get_stylesheet(), 'Styles returned from "::get_stylesheet()" with top-level background styles type does not match expectations' );
 
 		$theme_json = new WP_Theme_JSON_Gutenberg(
@@ -4852,7 +4852,7 @@ public function test_get_top_level_background_image_styles() {
 			)
 		);
 
-		$expected_styles = "body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}html{min-height: calc(100% - var(--wp-admin--admin-bar--height, 0px));}body{background-image: url('http://example.org/image.png');background-position: center center;background-repeat: no-repeat;background-size: contain;}";
+		$expected_styles = "body { margin: 0; }.wp-site-blocks > .alignleft { float: left; margin-right: 2em; }.wp-site-blocks > .alignright { float: right; margin-left: 2em; }.wp-site-blocks > .aligncenter { justify-content: center; margin-left: auto; margin-right: auto; }:where(.is-layout-flex){gap: 0.5em;}:where(.is-layout-grid){gap: 0.5em;}body .is-layout-flow > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-flow > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-flow > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignleft{float: left;margin-inline-start: 0;margin-inline-end: 2em;}body .is-layout-constrained > .alignright{float: right;margin-inline-start: 2em;margin-inline-end: 0;}body .is-layout-constrained > .aligncenter{margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > :where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width: var(--wp--style--global--content-size);margin-left: auto !important;margin-right: auto !important;}body .is-layout-constrained > .alignwide{max-width: var(--wp--style--global--wide-size);}body .is-layout-flex{display: flex;}body .is-layout-flex{flex-wrap: wrap;align-items: center;}body .is-layout-flex > *{margin: 0;}body .is-layout-grid{display: grid;}body .is-layout-grid > *{margin: 0;}html{min-height: calc(100% - var(--wp-admin--admin-bar--height, 0px));}:where(body){background-image: url('http://example.org/image.png');background-position: center center;background-repeat: no-repeat;background-size: contain;}";
 		$this->assertSame( $expected_styles, $theme_json->get_stylesheet(), 'Styles returned from "::get_stylesheet()" with top-level background image as string type does not match expectations' );
 	}